Move message handlers that don't belong in RenderProcessHostImpl to their own files.

content/browser/renderer_host/mhtml_generation_message_filter.h

Index: content/browser/renderer_host/mhtml_generation_message_filter.h
diff --git a/content/browser/renderer_host/mhtml_generation_message_filter.h b/content/browser/renderer_host/mhtml_generation_message_filter.h
new file mode 100644
index 0000000000000000000000000000000000000000..b318abe43f587970f0e2b27ca2429cb43e0afdc6
--- /dev/null
+++ b/content/browser/renderer_host/mhtml_generation_message_filter.h
@@ -0,0 +1,32 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_MHTML_GENERATION_MESSAGE_FILTER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_MHTML_GENERATION_MESSAGE_FILTER_H_
+#pragma once
+
+#include "base/compiler_specific.h"
+#include "content/public/browser/browser_message_filter.h"
+
+namespace content {
+
+class MHTMLGenerationMessageFilter : public content::BrowserMessageFilter {
+ public:
+  explicit MHTMLGenerationMessageFilter();
+
+  // content::BrowserMessageFilter implementation.
+  virtual bool OnMessageReceived(const IPC::Message& message,
+                                 bool* message_was_ok) OVERRIDE;
+
+ private:
+  virtual ~MHTMLGenerationMessageFilter();
+
+  void OnSavedPageAsMHTML(int job_id, int64 mhtml_file_size);
+
+  DISALLOW_COPY_AND_ASSIGN(MHTMLGenerationMessageFilter);
+};
+
+} // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_MHTML_GENERATION_MESSAGE_FILTER_H_